1. Field of the Invention
The present invention relates to an electrophotographic copier, and more particularly to an electrophotographic copier employing a photoconductive belt as a photoconductive body.
2. Description of the Prior Art
Electrophotographic copiers according to the Carson process (copiers, hereafter) utilize a drum or belt as a photoconductive body. No matter which photoconductive body may be employed, such processing devices as a charger, an exposure device, a transcribing device, a fixing device, a cleaning device, and a paper feeding device are disposed around the photoconductive body.
In copiers employing a drum, it is necessary for miniaturizing the machine body to reduce the diameter of the drum or the sizes of the above processing devices. But, for reducing the drum diameter, there is a technical limit from the view point of the characteristics of the photoconductive belt such as sensitivity to light and span of life. For reducing the processing device sizes, there are a lot of problems to be solved unless epoch-making processing technology would appear.
To overcome the above problems, it would be effective to use a belt as the photoconductive body, because the belt itself could be made compact and the degree of freedom in the arrangement of the above processing devices could be increased. But, actually, it is quite difficult to cause the belt to travel stably without complicated mechanism or parts. So, almost all the copiers now on the market employ a drum; there are few copiers which employ a belt for the purpose of miniaturizing the body size.